1. Industrial Field of the Invention
The present invention relates to a joy stick mechanism for an ophthalmic apparatus moving the optical apparatus on a fixed mount vertically and horizontally, to thereby position it with respect to an eye to be examined.
2. Description of the Prior Art
An ophthalmic apparatus, such as a fundus camera, is provided with a mechanism for positioning an optical system of the apparatus with respect to an eye to be examined. As this positioning mechanism, there has been known a sliding mechanism whereby a carrier on which the optical system of the apparatus is mounted is slid on a fixed mount when an operation stick or a joy stick is operated.
As this joy stick, there has also been known a joy stick with a mechanism whereby the outer periphery of the joy stick is rotated to move the optical system vertically. In such an apparatus, rotational movement of the joy stick is transmitted to the vertical movement mechanism through a combination of a belt and gears, and so forth.
Further, there has been known a switch mechanism provided on the top of a joy stick use it as a switch for photographing and measurement.
The applicant of the present application suggested, in Japanese Patent Examined Publication No. 3-1689 `Joy Stick Mechanism`, an apparatus including a shaft which is located on the axis of a joy stick and which can be rotated and inclined (turned), a rotating knob attached on an upper outer-peripheral portion of the shaft, an operation button provided on the top of the rotating knob, a turning knob which is attached on the outer periphery of a lower portion of the rotating knob and which is prevented from rotating, and a switch provided inside of the turning knob, wherein the operation button is provided with a connecting rod which has a ring-like plate to be connected to the switch.
However, the conventional joy stick involves a problem that the structure is extremely complicated and a problem that location of the joy stick is restricted. Moreover, in order to transmit rotation of the joy stick to a vertical movement mechanism, a space for installing gears and a belt is required, which results in another problem that the apparatus is increased in size.
Furthermore, in the case of the apparatus with an operational mechanism for moving the optical system vertically, which is provided independently from the joy stick, it is necessary to release the hand of an operator from the joy stick so as to operate this operational mechanism. Thus, the operational efficiency is extremely deteriorated. Besides, in the case of an apparatus which requires strictly accurate positioning, it involves a problem that the operation is difficult.